Neuroanatomy Flashcards
week 5
what is the telencephalon?
- cerebrum (outside= cortex, inside= subcortical regions)
- part of the forebrain
- contails the basal ganglia
- divided symetrically left and right cerebral hemispheres (cross-lateralisation)
what are the sub-regions of the telencephalon?
- cerebral coretx= thin outer layer of neural tissure, responsible for many “high-order” functions
- Limbic system: interconnected nuclei & cortical structures located in telencephalon & diencephalon important for olfaction (smell), emotions, learning & memory
- Basal Ganglia: Group of nuclei located beneath cortical surface vital for movement
what is the cerebral cortex substructure?
- Cortex surface enlarged (x3) by folding
- Gyrus: bulges
- Sulcus: small grooves
- Fissure: large grooves (larger sulci)
- Rostral region= front (nasal side)
- Prominent features:
- central sulcus
- lateral fissure
- longitudinal fissure
what is grey matter?
the cerebral cortex- outer layer composed of cell bodies, dendrites & glia
what is white matter?
Inner layer composed of myelinated axons
what are the 4 lobes of the cerebral cortex?
- Frontal lobe (blue): anterior part of cortex, rostral to parietal lobe & dorsal to temporal lobe
○ Rostral to the parietal lobe - Parietal lobe (yellow): caudal to frontal lobe & dorsal to temporal lobe
- Occipital lobe (red): caudal to parietal & temporal lobes
* Most caudal - Temporal lobe (green): rostral to occipital lobe & ventral to parietal & frontal lobes
which lobe of the cerebral cortex is ventral to the parietal lobe?
temporal lobe
which lobe of the cerebral cortex is caudal to the temporal lobe?
occipital lobe
what is the prefrontal cortex?
the most rosteral region of the cortex
* planning and strategies
* 2 main parts:
1. executive functioning (schizophrenia & depression), higher order thinking, goal directed
2. personality, impuse control and mood (addiction), decision making, growth and development
what is the prefrontal cortex?
- Central location of cognitive control and functioning
- Main site of action for dopamine regulating attention, impulse inhibition, memory, cognitive flexibility, motivation, reward management, personality.
- Coordinates voluntary movement
- Planning
- Higher order thinking
- Emotional expression
- Language production (Broca’s area)
what are the main fucntions of the prefrontal cortex?
- Executive functions:
- Self-control
- Planning
- decision making
Unlikely one single brain region controls each.
what are the sensory fucntions of the primary cortex?
- 3 primary sensory cortices:
1. Primary visual cortex: occipital lobe
2. Primary auditory cortex: temporal lobe
3. Primary somatosensory cortex: parietal lobe - Predominantly processed contralaterally
what are the main motor fucntions of the cerebral cortex?
- primary motor cortex contrls the voluntary movements of the skeletal muscls
- located in the front of the central sulcus (frontal lobe)
- connections are contrelateral
what are association cortices?
recieve information from relevant primary cortices.
what is the sesnory association cortex?
- Perception & memories
- Located behind central sulcus
what is the motor association cortex?
- Directly controls PMC and thus behaviour
- Includes premotor cortex
- Located in front of PMC
what is the function of the parietal lobe?
- Perception of awareness and space
- Somatosensory cortex that integrated all the sensory systems
what is the function of the temporal lobe?
- Recognition, identification and awareness
- Auditory cortex
what is the fucntion of the occipital lobe?
- processing of visual information from the retina
what is meant by the term lateralisation?
- Two hemispheres do not perform identical functions
- Lateralised: Some functions primarily located on 1 side
○ Left hemisphere: info analysis, recognising serial events, controlling sequences of behaviour
○ Right hemisphere: synthesis of information (holistic)
what are the fucntions of the left side of the brain?
- analytical thought
- detail oriented perception
- orded sequencing
- rational thought
- verbal
- cautios
- planning
- maths/science
- logic
- right field vision
- right side motor skills
what are the fucntions of the right side of the brain?
- intuitive thought
- holistic perception
- random sequencing
- emotional thought
- non-verbal
- adventurous
- impulsive
- creative writing/ art
- imagination
- left field vision
- left side motor skills
what is the corpus callosum?
- large bundle of axons
- interconnects corresponding regions of cortex on each hemisphere
why do patients have the split brain surgery?
to cure severe epilepsy
what does the split brain surgery tell us about the human brain?
Each side of the brain work through communicating to the other
what is the split brain surgery?
- Corpus Callosum cut (relieves epileptic seizures)
○ Two hemispheres operate independently - Speech: left-hemisphere
○ Only left can communicate it’s actions or thoughts - Reports of left and right hemispheres conflicting
- Olfactory information is an exception to contralateral representation of sensory information
what is the limbic system?
cortical and subcortical structures concerned with emotions
what are the 3 central regions that are part of the limbic system?
- Amygdala
- Hippocampus
- Singular gyrus: innovated the limbic loan.
* Also includes the mammillary bodies and the fornix with are relays for the emotions.
what is the hippocampus?
- forebrain structure of temporal lobe
- looks like a sea horse
what are the main fucntions of the hippocampus?
- learning and memory (imcluding limbic cortex)
- storing and retrieving explicit memories
- helps with directions
what was HM’s condition?
cracked his head when he fell and experienced seizures as a result
how did patient HM’s seizures affect his abilities?
- Dropped out of high school
- Memory after removing hippocampus was effected
- Only slight episodic memory.
what did patient HM’s surgery teach us about memory?
- Removed the hippocampus, most of his memories were forgotten and he couldn’t make anymore memories.
- Redefined what memory even meant: although he couldn’t form new memories, he could still remember basic information to finish a sentence or find a certain room
- Memory may not be stored throughout the brain
- Distinction between short term and long term memory- different brain regions
- Remember information for 15 minutes if continuously recited, forgot the test took place 5 minutes later.
- Without hippocampus to perform memory consolidation- memory was forgotten
- Unconscious motor centres remembered what the conscious mind had forgotten- had to draw a third star between two others.
- Procedural memories were intact.
what is the amygdala?
- In the interior of rostral temporal lobe
- Set of nuclei
- along with regions of the limbic cortex, it is involved in multiple aspects of emotions.
- Vital for decoding emotion, particularly to threatening stimuli
- Fight or flight (and stress)= central region
- Activates brain regions to release adrenaline and ACTH.
what are the main functions of the amygdala?
- Fear, fear learning & aggression: stress and self-defence
- Turning on stress response:
- Adrenaline
- AcTH → Cortisol
- Stress responses to threatening stimuli
- Fight or flight
- Automatic: real & perceived threats
what would happen if we didnt have an amygdala?
we would have no fear resonse or fight or flight.
how do the amygdala and hippocampus work together?
- The amygdala and hippocampus work together
- Amygdala receives connections from hippocampus
- Why strong emotions may be triggered by memories
○ e.g., PTSD - Reduced hippocampal volume
- Reduced ventromedial prefrontal cortex
- Increased activity of amygdala
what do patients with impaired amygdala activity show?
lack of loss aversion (“unafraid” to gamble)
what is the cingulate girus?
- Part of limbic cortex
- Occupies subcortical region of the limbic lobe.
- Located above corpus callosum
- Related to managing emotions
- Relay system
what are mammilary bodies?
- Protrusion on bottom of brain
- Memory recollection
- Link with hippocampus through the hypothalamus
- Links with the hypothalamus through the fornix
- Part of hypothalamus
what is the fornix?
- Bundle of axons connecting hippocampus to brain regions including mammillary bodies
- Largest pathway through the brain.
what is the basal ganglia?
- Part of telencephalon
- Related to control of movement
- Group of subcortical nuclei
- Tightly interconnected
- Involved in control of movement (and procedural memory)
- Links to cerebellum
what is the fucntion of the basal ganglia?
- Process info from several regions of cerebral cortex
- Returns info to motor cortex via thalamus
- Helps process information that is sent to the thalamus
- Operating in conjunction with a loop involving the cerebellum
- Select & trigger well co-ordinated voluntary movements
- Important in Parkinson’s & Huntington’s disease
what is the diencephalon?
- Division of forebrain
- Located between telencephalon & mesencephalon (midbrain)
○ Mediates the two - Surrounding the third ventricle
- Two main structures:
thalamus & hypothalamus
- Located between telencephalon & mesencephalon (midbrain)
whata re the main fucntions of the diencephalon?
- Relays sensory information (Thalamus)
- Controls many autonomic functions of PNS Connects endocrine system to NS (hypothalamus)
- Involved in emotions and memories alongside limbic system (hypothalamus)
○ Start of the endocrine system
○ Chemical mechanism of communication
§ Last longer
Electrical impulses throughout the system
what is the structure of the thalamus?
- Largest portion of diencephalon
- Means “inner chamber”
○ Key part between the cerebrum cortex, cerebellum and midbrain - Dorsal part of diencephalon
- Two lobes connected by bridge of grey matter (Massa intermedia) which pierces middle of third ventricle
Made up of a number of nuclei
- Means “inner chamber”
what are the main fucntions of the thalamus?
- Receiving and relaying auditory, visual and somatosensory sensory signals to the cerebral cortex
○ gateway to the cortex
○ Mediator and relays information between the body and the cerebrum cortex.
○ Controls levels of arousal and tiredness levels.- Controlling sleep and awake states
- Motor control
- Memory and emotions
Linked to the RAS (recirculatory activation system)
what is the thalamic nuclei?
- Some nuclei are involved in general excitability of cerebral cortex
- Other nuclei act as relay stations for sensory and non-sensory information
○ Emotional memory - Non-sensory (motor) information:
○ Ventrolateral nucleus - Sensory information:
○ Lateral geniculate nucleus (vision)
Medial geniculate nucleus (audition)
- Other nuclei act as relay stations for sensory and non-sensory information
which lobe of the cerebral cortex is caudal to the temporal lobe?
occipital
which lobe of the brain is responsible for higher order thinking?
frontal
which lobe of the brain is responsible for comprehension of language?
temporal
which lobe of the brain is responsibel for understanding where we are in spcae and time?
parietal
which lobe of the brain is responsible fro language production?
frontal
